Presses for bending sheet metal



W. BEYELER June 27, 1967 Filed April 26, 1965 June 27, 1967 w. QEYELER 3,327,515

PRESSES FOR BENDING SHEET METAL Filed April 26, 1965 meets-Sheet 2 7 lie lle J/d ,I9

Ilf l8 /7 United States Patent 3,327,515 PRESSES FOR BENDING SHEET METAL Willy Beyeler, Route de Morges, Crissier, Lausanne, Switzerland Filed Apr. 26, 1965, Ser. No. 450,660 Claims priority, application Switzerland, Apr. 24, 1965,

6 Claims. (Cl. 72453) The present invention relates to presses and particularly to presses for bending sheet metal.

Presses for bending sheet metal, for example those which are operated hydraulically, present the problem that the support members or beds which carry the matrices or dies are subject to substantial flexing during the bending operation. In known machines, this flexing is uncontrollable and is sufficiently serious that the bent piece has perceptibly different angles at its ends than in intermediate portions.

It is an object of the present invention to provide a sheet metal bending press which overcomes this objection. In accordance with the invention, a press comprising a frame, a fixed bed or support member, a second support member vertically movable on the frame toward and away from the stationary support member by means of at least three jacks of which two are located near the ends of the movable support member and one or more are disposed inermediate the end jacks, is provided with means for interrupting movement of the end jacks before completion of movement of the intermediate jack or jacks whereby the movable support member is flexed by continued movement of the intermediate jack or jacks after movement of the end jacks has been interrupted. This fiexion of the movable support member is transmitted through the dies and the sheet metal being bent to the fixed support member mounted on the frame. Preferably the regulation of the means for interrupting movement of the end jacks is effected by a common control mechanism so that both of said means are regulated simultaneously and identically.

The objects and advantages of the invention will be more fully understood from the accompanying description and claims in conjunction with the accompanying drawings in which:

FIG. 1 is a front view of a press in accordance with the invention with portions broken away to show internal construction,

FIG. 2 is an end view partially in section taken approximately on the line 11-11 in FIG. 1, and

FIG. 3 is an enlargement of a portion of FIG. 1.

The press shown by way of example in the drawings comprises a frame formed of two lateral uprights 1 and 2 which are connected with one another by two upper transverse members 3 and 4 and by a lower transverse member 5 which constitutes the stationary support member or bed of the press carrying a matrix 6.

Directly above the stationary bed 5, there is provided a movable support member or bed 7 formed of a relatively thick, approximately rectangular plate which is vertically slidable between guides 8a and 812 on the frame. On the lowe longitudinal edge of the plate 7 there is mounted a bending die 9 designed to cooperate with the matrix 6 in bending sheet metal.

In the plate 7, constituting the movable support member or bed of machine, there are provided four openings or windows 10 of which only two are visible in FIG. 1. In each of the openings 10 there is mounted a hydraulic jack, the jacks near the end of the plate 7 being designated by the reference numeral 11 while the intermediate jacks are designated by the reference numeral 12. Each of the 3 ,3215 1 5 Patented June 27, 1957 "ice jacks comprises a cylinder mounted on the transverse frame members 3 and 4.

Each of the jacks 11 comprises a cylinder 11b and a piston 11d slidable in the cylinder and having a piston rod 11a extending out through opposite ends 11e of the cylinder and abutting on the upper and lower edges respectively of the opening 10 in which the jack is mounted. Tight abutment of the piston rod 11a with the upper and lower edges of the opening 16 is effected by means of intermediate wedges or chocks which are of adjustable height and have convex faces fitting into concave depressions provided in the opposite ends of the piston rod 11a.

Each of the intermediate jacks 12 disposed between the end jacks 11 comprises a corresponding cylinder 12b and a piston 12d slida'ble in the cylinder and provided with a piston rod 12a which extends out of the lower end of the cylinder 12!) and abuts on the lower edge of the opening which constitutes the corresponding window 10 in the vertically movable plate 7.

Hydraulic fluid is supplied to the hydraulic jacks 11 and 12 through a suitable hydraulic system (not shown) under control of a foot pedal 13 to actuate the jacks to raise and to lower the movable member 7. During its descent in the slides 8a and 8b, the plate 7 is guided parallel to the table by means of mechanism 14 comprising a torsion shaft 14a and crank arms 14b, the Weight of the plate being at least partially counterbalanced by torsion of the shaft 14a.

In the press shown in the drawings, the end jacks 11 comprise controllable means for interrupting movement of the end jacks before completion of movement of the intermediate jacks 12. Such mechanism is shown by way of example in FIG. 3 as comprising a sleeve 15 which is slidably mounted on the lower portion of the piston rod 11a. The peripheral surface of the sleeve 15 is provided with a spiral thread 15a engaged by an annular nut 16 which rests on the lower end 11s of the cylinder and is provided on its peripheral surface with a circular series of teeth 16a. The teeth 16a of the nut 16 are engaged by an endless worm or screw 1'7 carried on a rotatable shaft 18 which can be rotated either manually or mechanically. The screw 17 is accomodated in an enlargement 11 of the cylinder 11b and the shaft 18 extends out through an opening provided with a suitable packing or seal to preserve the fluid-tightness of the cylinder 11b. Means is provided for holding the sleeve 15 against rotation while permitting its axial movement. In FIG. 3 such means is illustrated as a threaded stud 19 which is screwed into a threaded opening in the cylinder wall and has a reduced inner end portion engaging in a longitudinal groove 15!) provided in the sleeve 15.

As the sleeve 15 cannot move angularly, but only axially on the piston rod 11a, it will be apparent that rotation imparted to the nut 16 by action of the screw or worm 17 produces axial sliding movement of the sleeve 15 either upwardly or downwardly according to the direction of rotation imparted to the screw 17. The sleeve 15 and nut 16 thus constitute an abutment of variable length between the piston 11d and the inner face of the lower end lle of the cylinder 11b. There is thus provided an adjustable stop limiting downward movement of the piston 11d in the cylinder 11b.

Preferably the drive of the screws 17 for the two end jacks 11 is synchronized with one another in the manner that the displacement and the position of the sleeves 15 of the two end jacks are rigorously identical with one another.

In practice, the axial position of the sleeves 15 of the end jacks 11 is chosen in such manner that the movement of the piston rods 11a of these jacks in a downward direction is interrupted before the piston rod 12a of each of the intermediate jacks 12 has terminated its downward axial movement. In this manner, the movable support 12 is caused to flex by the continued downward pressure exerted by the intermediate jacks 12 while the ends of the support member 7 are held against further vertical downward movement by abutment of the upper ends of the piston rods 11a of the end jacks 11 with the upper edges of the respective openings 10 in which the jacks are located. This flexing is absolutely controllable by the adjustment of the sleeves 15 and by the hydraulic pressure, which is regulated by a valve.

The flexion of the movable support member 7 is transmitted to the stationary support member or bed 5 in such manner that the sheet metal is pressed uniformly between the matrix 6 and die 9 so as to be bent uniformly throughout its length with minimum tolerance.

While the press shown by way of example in the drawings and herein particularly described is provided with four hydraulic jacks, it will be evident that it could have a minimum of three or on the contrary, a number greater than four, it being intended that the presses will always have a jack of the kind indicated by the reference numeral 11 in FIG. 1 at each extremity of the movable support member or bed, the number of intermediate jacks 12 varying as a function of the length of the press.

Moreover, it will be clear that interruption of the movement of the end jacks can be effected by means of a stop or abutment constructed differently from that represented by way of example in the drawings and that other means may be provided for effecting the opposing pressure in the cylinders of these jacks.

What I claim is:

1. A press for bending sheet metal comp-rising a frame, a first support member fixed on said frame, a second Support member vertically movable on said frame toward and away from said first support member and having at least three openings therein, a matrix and a die fixed respectively on said support members, means for moving said movable support member comprising at least three jacks disposed respectively in said openings, two of said jacks being'located near the ends of said movable support member and at least one jack being disposed intermediate said end jacks and regulatable means for interrupting movement of said end jacks before completion of movement of said intermediate jack whereby said movable support member is flexed and fiexion of said movable support member is transmitted through said matrix and die and the sheet metal beingbent to said fixed support member.

2. A press according to claim 1, further comprising means for simultaneously regulating said means for interrupting movement of said end jacks.

3. A press according to claim 1, in which each of at least said end jacks comprises a cylinder fixed to said frame, a piston reciprocable in said cylinder and a piston rod extending through said cylinder and abutting opposite edges of the respective said opening.

4. A press according to claim 3, in which said means for interrupting movement of each of said end jacks comprises an externally threaded sleeve slidable on said piston rod, a nut on said sleeve and means for rotating said nut to provide an abutment of variable length between said piston and an end of said cylinder.

5. A press according to claim 4, in which said nut is provided on its periphery with a circular series of teeth and in which said means for rotating said nut comprisesv a worm on a rotatable shaft engaging said teeth whereby said nut is rotated by rotation of said shaft.

6. A press according to claim 4, in which said nuts of both of said end jacks are driven in synchronism with one another.

References Cited UNITED STATES PATENTS 2,133,477 10/1938 Schade 72412 3,241,350 3/1966 Giordano 72-412 CHARLES W. LANHAM, Primary Examiner.

G. P. CROSBY, Assistant Examiner. 

1. A PRESS FOR BENDING SHEET METAL COMPRISING A FRAME, A FIRST SUPPORT MEMBER FIXED ON SAID FRAME, A SECOND SUPPORT MEMBER VERTICALLY MOVABLE ON SAID FRAME TOWARD AND AWAY FROM SAID FIRST SUPPORT MEMBER AND HAVING AT LEAST THREE OPENINGS THEREIN, A MATRIX AND A DIE FIXED RESPECTIVELY ON SAID SUPPORT MEMBERS, MEANS FOR MOVING SAID MOVABLE SUPPORT MEMBER COMPRISING AT LEAST THREE JACKS DISPOSED RESPECTIVELY IN SAID OPENINGS, TWO OF SAID JACKS BEING LOCATED NEAR THE ENDS OF SAID MOVABLE SUPPORT MEMBER AND AT LEAST ONE JACK BEING DISPOSED INTERMEDIATE SAID END JACKS AND REGULATABLE MEANS FOR INTER- 